package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;
import static com.hmdp.utils.SystemConstants.DEFAULT_PAGE_SIZE;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;


    @Resource
    private CacheClient cacheClient;
    /**
     * 按id查询商铺
     *
     * @param id
     * @return
     */
    @Override
    public Result queryById(Long id) {
       //缓存穿透
        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);

//        //用互斥锁解决缓存击穿
//        Shop shop = queryWithMutex(id);

//        //用逻辑过期解决
//        Shop shop = queryWithLogicalExpire(id);
//        //用逻辑过期解决
//        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY,id,Shop.class,this::getById,CACHE_SHOP_TTL,TimeUnit.MINUTES);
        if (shop == null) {
            return Result.fail("店铺不存在！！");
        }

        return Result.ok(shop);
    }


    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * 逻辑过期解决缓存击穿问题
     *
     * @param id
     * @return
     */
    public Shop queryWithLogicalExpire(Long id) {
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        //从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3.不存在
            return null;
        }
        //4.缓存存在，需要把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1未过期，直接返回店铺信息
            return shop;
        }
        //5.2 已过期，需要缓存重建
        //6.缓存重建
        //6.1 获取互斥锁
        String lockKey = CACHE_SHOP_KEY + id;
        boolean isLock = trylock(lockKey);
        //6.2 判断互斥锁是否获取成功
        if (isLock) {
            // TODO 6.3 成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShop2Redis(id, 1800L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }
        //6.4 返回过期数据
        return shop;
    }


    public Shop queryWithMutex(Long id) {
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        //从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断命中是否为空值
        if (shopJson != null) {
            //返回一个错误信息
            return null;
        }
        // todo 4 实现缓存重现
        // 4.1 获取互斥锁
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        Shop shop = null;

        try {
            boolean islock = trylock(lockKey);
            //4.2 判断是否获取成功
            if (!islock) {
                //4.3 失败，则休眠成功
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4 成功，更具id查询数据库
            shop = getById(id);
            //5.查询到的店铺不存在
            if (shop == null) {
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6.存在，写入redis
            // todo 在根据id查询商家信息时，把信息存入缓存，同时设置有效时间
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            // todo 释放互斥锁
            unlock(key);
        }
        //7.返回
        return shop;
    }

    /**
     * 缓存穿透
     *
     * @param id
     * @return
     */
    public Shop queryWithPassThrough(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断命中是否为空值
        if (shopJson != null) {
            //返回一个错误信息
            return null;
        }
        //4.不存在
        Shop shop = getById(id);
        //5.查询到的店铺不存在
        if (shop == null) {
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //6.存在，写入redis
        // todo 在根据id查询商家信息时，把信息存入缓存，同时设置有效时间
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;
    }

    /**
     * 获取锁工具
     *
     * @param key
     * @return
     */
    private boolean trylock(String key) {
        stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);

        return BooleanUtil.isTrue(false);
    }

    /**
     * 删除锁工具
     *
     * @param key
     */
    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }

    /**
     * 逻辑过期，给数据封装一个逻辑过期时间
     *
     * @param id
     * @param expireSeconds
     */
    private void saveShop2Redis(Long id, Long expireSeconds) {
        //1.查询店铺数据
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));

    }


    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        //1.跟新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());

        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if(x==null || y==null){
            Page<Shop> page = query().eq("type_id", typeId).page(new Page<>(current, DEFAULT_PAGE_SIZE));
            return Result.ok(page.getRecords());
        }
        //2.计算分页参数
        int from=(current-1)*DEFAULT_PAGE_SIZE;
        int end=current*DEFAULT_PAGE_SIZE;
        //3.查询redis、按照距离排序，分页 结果;shopId、distance,
        String key=SHOP_GEO_KEY +typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().limit(end)
                );
        //4.解析出id
        if (results==null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size()<=from){
            return Result.ok(Collections.emptyList());
        }
        //4.1截取from~end部分
        List<Long> ids=new ArrayList<>();
        Map<String,Distance> distanceMap=new HashMap<>(list.size());
        list.stream().skip(from).forEach(result ->{
            //4.2 获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //4.3 获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        //5.根据id查询shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //6.返回
        return Result.ok(shops);
    }
}
